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Sunday, January 06, 2008

Carolina Wrens, A Favorite Full-time Resident by Ro Wauer

Even in winter, when our temperatures seem to temper the enthusiasm of most other birds, our Carolina wrens are still active and cheerful. They still are busy searching for bugs and other tiny creatures about our yards, and every now and then they will stop and sing their perky songs. Then they will continue their search in every possible corner and hole where they could possible discover some choice morsel. No flowerpot, chair, bench, utensil, or hole and crevice in trees and shrubs are missed. And unless we approach close enough spook them into a retreat, they seem to ignore our presence. They go about their search with impunity.

Carolina wren songs are some of our most commonly heard birdsongs, and they can usually be heard during all the daylight hours. Even in winter, when most other songbirds are quiet, Carolina wrens are rarely silent for more than a few minutes at a time. And what is also fascinating is their ability to sing a number of tunes. Most songs are a loud and clear ringing sound, and usually 3-syllabeled, but they can also be 2-syllabeled. And most songs are repeated three to five times or more. Although Carolina wren songs usually follow a “tea-kettle” format, they can just as well be more of a “weedle” format, a huge variation, or a wild combination. In fact, Paul Ehrlich and colleagues , in “The Birder’s Handbook,” point out that male Carolina wrens “sing 27 to 41 different song types, singing one song repeatedly before switching to different song types; neighboring males frequently match song types.” In addition, males and females duet, a behavior more typical of the tropical wrens. And as far as their call notes are concerned, they can be just as varied with a descending “tiirreee” or buzzing, chattering, or scolding sounds.

Carolina wrens, for those readers who do not know this bird, are easy to identify. It is the largest of our wrens. It is a stubby bird with a heavy dark bill and a rufous back, buffy underparts, and a thick, conspicuous white eyebrow stripe. It has a fairly long, rusty tail, barred with narrow black lines, and is often cocked or switched back and forth. And it has a habit of bobbing up and down. Carolina wrens are very different from the smaller Bewick’s and house wrens that we could possible see in our yards and woods.

For the most part, Carolina wrens are birds of the eastern half of the United States, where they can be present in habitats of all kinds. They are equally at home in deep forests to streamsides and backyards. Their range extends northeast into Maine, but not into the Canadian Provinces. The western extension of their range barely reaches West Texas, although in recent years it has been recorded on the eastern side of Big Bend National Park on several occasions. Like so many other birds, range expansion has become accepted.

Carolina wrens seem to get along just find in human habitations, even constructing their grass and stick nests in flowerpots and folded sheets that are left on the line too long. More typical nesting sites include cavities in trees and stumps, but they frequently utilize deserted woodpecker holes and nest boxes. The nests themselves are bulky structures of leaves, weeds and other materials and built by both parents. Incubation is done principally by the female, but the male brings food to feed the sitting female. Both parents feed the nestlings, but if the female moves to another nest to lay additional eggs, he will continue feeding the youngsters. And unlike most songbirds, Carolina wrens mate for life, maintaining their bond year-round. It is possible to see young birds almost any time of year.

Behavior of Carolina wrens is truly fascinating, not just because they are so obvious, but also because of their strange activities. For instance, they are one of the few songbirds that, like roadrunners, often perch in a sunbathing position, exposing their rump to the sun’s rays. They often remain in that position for several minutes. This is most common during cooler winter days.